Clamp terminal construction



Dec.'8, 1942. w, s E o 2,304,711

CLAMP TERMINAL CONSTRUCTION Filed Jan. 10, 1941 Z M W Til: .5.

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Patente I E a s a? raarmrar. coNs'rapc'rroir Thomas W. Sheraton, West Hartford, Court, as signer to The Arrow-Hart 8r Hegeman Electric Company, Hartford, Conn, a corporation of Connecticut Application January 10, 1941, Serial No. 374,003

1 Claim.

This invention relates to a novel construction of a clamp-type of terminal suitable for use in making electrical connections. The terminal, although useful generally in the electrical arts,

is particularly adapted to use in connection with attachment plug receptacles, switches, pilot lights and related types of electrical wiring de-' vices.

It is an object of my invention to provide an improved construction of clamp-type terminal 10 which will more effectively grip electric wires to r hold them against twisting and from being pulled out of position.

Other objects and advantages of my invention will become apparent as it is described in connection with the accompanying drawing,

In the drawing- 'Fig. 1..is a perspective view of the clampmember of my new clamp-type terminal.

Fig. 2 is a plan view of the assembled terminal gripping an electric wire.

Fig; 3 is a section view taken along line 3-3 of Fig. l.

Referring to the drawing, the terminal comprises a clampingmember ill, preferably stamped from sheet metal into the form illustrated in Fig. 1, having a back 10a with a screw-threaded aperture i2 therein. From each corner of the back, fingers iflb and I00 extend. The fingers lob at the right hand edges are struck into substan- 3o tially perpendicular-,relation to the back while the fingers l0c-'-at the left hand edge-are struck at an oblique angle to the back to accom modate various sizes of wire. Between the fingers I00 and the screwthreaded aperture i2,

the inside surface of the back is provided with divergent scorings Ma and Mb. The scorings Ila are inclined downwardly'from the horizontal center line of the back, being directed preferably beneath the aperture i2, while the scorings 40 Mb are inclined upwardly from the center line being directed preferably above the aperture I2. The individual ribs or teeth of the scorings preferably are parallel. Of course, the two series of scorings can be reversed in direction so as to diverge outwardly.

The clamp member Ill is designed to be clamped to any fixed terminal "part of a switch,

receptacle, or other electric device, by means of a a terminal screw l6 whose shank threads into the aperture l2 and whose head may abut one side of a conductive plate or strip of metal I8- such as, for example, the connecting bar between the contact fingers of a conventional duplex attachment plug receptacle. (Those skilled in the art will understand that in conventic Jal duplex attachment plug receptacles, the contact fingers and the connecting bar portion are customarily stamped as one piece from sheet metal.) The shank l8 of the terminal screw 00 passes through an aperture in the connecting bar (Cl. l'i3259) It, the aperture being slightly larger'in diameter than the diameter of the shank.

When the parts are assembled, a wire 20 may be'inserted between the clamp member i0 and the connecting bar I8 in position to be engaged and gripped by the divergent scorings Ma and Hit: onthe clamp member when the terminal screw is turned to move the clamp member toward the plate i8. Due to the oblique character of the fingers I00, the clamp member may accommodate wires of different diameters so that the terminal is adaptable in many fields of I use and may be used without particular regard I to the size of conductor to be connected to the electrical device.

I'have found by actual use and test, that the provision of the divergent scorings affords a gripping action upon the conductor which is far a superior ,to any of the many means of frictional holding that I'have known. The wires are held very firmly against twisting, as well as against any pull which would tend to move the wires axially out of their position. The gripping action is so firm that an effort to turn the wire about its own, axis will result in the wire itself twisting while the portion which is gripped by the divergent scorings remains fixed.

I do not limit the invention to the specific form or number of divergent scorings illustrated, since modifications within the scope of the invention will occur to those skilled in the art.

I claim:

In a clamp type terminal, a fixed electrically conductive member having an opening therethrough, an electrically.- conductive terminal screw having a shank passing through said opening, an electrically conductive clamp member having one end bent in a direction substantially perpendicular to the main body of said clamp member and the other end bentin a direction oblique to the main body of said clamp member to accommodate bare metal conductor wires of 'diflerent sizes, one of said electrically conductive members having a screw threaded aperture for the reception of the shank of said terminal screw, said electrically conductive clamp member having a plurality of series of parallel sharp edged ribs directed in divergent directions from of and said bbliquely bent portion thereof, to

aflordmeans to bite into and grip said bare metal conductor wires of different sizes, between said clamp member and said fixed member in metalto-metal contact therewith and cause the conduction of electrical current from said bare metal conductor wire through said ribs into said clamp member.

THOMAS W..SHENTON. 

